TORONTO – A week after the Supreme Court gave the government the constitutional go-ahead to expand marriage rights to gays and lesbians, a bitter battle has emerged in Parliament that is creating deep fissures in the Liberal and Conservative parties.

Polls indicate that a comfortable majority of Canadians actively support or passively accept legislation being prepared by Prime Minister Paul Martin to redefine marriage across the country. Already, courts in six provinces and one territory, all told covering 85 percent of the population of nearly 32 million, have struck down old marriage laws to allow gays and lesbians to wed. Only minor protests have occurred.

But pockets of dissent have emerged in rural areas and suburbs of Toronto with heavy immigrant and Muslim populations, putting as much as one-quarter of the governing Liberal caucus in the House of Commons in a political quandary. Martin has said Liberal backbenchers can vote their conscience but that Cabinet members must toe the party line in favor of the legislation.

Already, two members of the Cabinet have said they may have to resign and vote against the government. A few defections from the Cabinet, however, probably would not jeopardize final passage of the marriage legislation, which will be introduced when Parliament comes back into session late next month. The majority of Liberals supporting the bill will be joined by nearly all the members of the opposition Bloc Quebecois and New Democratic Party, along with a few Conservative members.

The greatest rancor has surfaced in the Conservative Party, which united social conservatives, libertarian conservatives and moderates from two parties last year.

Stephen Harper, the Conservative leader from Alberta, personally opposes expanding marriage rights, but he has tried to soft-pedal the issue to win more urban support and become competitive in socially liberal Quebec in national elections that could come next year.

His centrist stance has generated an outcry from right-wing Conservatives led by Alberta's premier, Ralph Klein, who said he was considering starting a national crusade to save the traditional definition of marriage.

Klein called on Harper to press the House of Commons to enact a rarely used constitutional loophole known as the "notwithstanding clause" enabling the legislature to override constitutional rights. Such a measure would overturn the lower court rulings in favor of same-sex marriage, although it stands virtually no chance of passage and would be viewed by many as a trampling of the Charter of Rights and Freedoms, Canada's bill of rights.

Martin has tried to exploit the split by accusing Harper of "a lack of courage and clear lack of leadership" and complimenting Klein for at least being "intellectually honest" enough to speak his mind.

Harper has said he plans to introduce amendments to the marriage legislation that would preserve the traditional definition of marriage as a bond between a man and a woman, guarantee equal rights and benefits for gay couples, and protect religious institutions that refuse to perform weddings for same-sex couples.

But without enacting the notwithstanding clause, Harper's amendments would not have force in the jurisdictions that already allow same-sex marriage, which encompass the vast majority of Canadians.